The invention is concerned with a cuvette for use with automatic chemical testing apparatus of the type used for making light transmittance measurements of liquid samples such as blood serum, to which various reagents have been added to cause chemical changes. Such apparatus is well-known and usually will process a plurality of liquid samples in small containers or cuvettes. There is a succession of samples which move through the apparatus, these samples being contained in the cuvettes.
Some apparatus will process the samples with different tests in which case all cuvettes may contain serum from a single patient but with different reagents added so that the reactions of the respective tests are different. Some apparatus will process samples from different patients but making the same type of tests for all, in which case the same chemical reagent or reagents will be added to each sample. Some apparatus can perform both types of procedures. The samples have to be identified with respect to the particular source and the particular test, many types of apparatus being capable of handling these problems, but the invention not being concerned with this.
In a typical apparatus, the blood sample is placed in the cuvette, a reagent added, the cuvette stirred and incubated to reach a certain temperature for a certain time while being mechanically stirred, and the resulting liquid mixture or compound interposed between a source of radiant energy and a transducer. The source of radiant energy is usually a beam of light of a certain wave length and the transducer is a photoresponsive device which will produce an electric signal that has a particular relationship with respect to the amount of light which has been absorbed by the mixture in the cuvette. The added reagent and the absorbance characteristic for certain types of chemical tests are known so that the signal from the transducer may be converted into values of certain constituents of the blood of the patient which was the source of the serum. The distance through the liquid sample is generally standardized as 10 millimeters.
The problems which are attempted to be solved by the invention herein may be stated generally as follows:
1. Known cuvettes use large amounts of expensive reagent because they are required to have a certain volume of the resulting mixture through which the beam of light must pass. PA1 2. Known cuvettes have large volumes because of the need to stir the contents and the requirement to accommodate the stirrer.
The invention provides a cuvette which is very small and yet which provides a standard beam transmission distance and accommodates a stirrer. It thus uses less reagent than generally used heretofore for making the same tests.
The form of cuvette which is taught by the invention is simple and economical to manufacture, enables positive location for use, is readily removed and disposed of from the apparatus with which it is used and yet provides efficiency in use of enabling stirring in a small volume which has the standard distance of transmission between walls thereof.